Value Document Verification Sensor With Velocity Correction
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Solution Overview
Problem
Existing sensors inaccurately determine the luminescence time constant of value documents at high transport velocities due to movement effects, leading to corrupted intensity profiles and systematic measurement errors among different sensor specimens.
Innovation Solution
A sensor is designed to correct the luminescence time constant by using sensor-specific parameters and correction factors tailored to the transport velocity, accounting for geometric tolerances and relative movement, allowing accurate determination and comparison of luminescence time constants across different sensor specimens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If value documents are transported at high velocity past the sensor for fast processing, then productivity is improved, but measurement precision deteriorates due to movement effects corrupting the intensity profile
Solution Approach 1:
The patent changes the reference frame from stationary sensor to moving sensor by applying a velocity correction factor to transform measurements taken in the moving frame back to the stationary frame. This allows accurate determination of luminescence time constants even when the value document moves at high velocity through the detection region.
2Measurement precision
If a stationary sensor is used for accurate luminescence measurement, then measurement precision is improved, but productivity deteriorates because the value document must be transported slowly
Solution Approach 1:
The patent replaces the mechanical constraint of slow document transport with a mathematical correction approach. Instead of physically slowing down the document to match sensor detection speed, the system uses velocity correction factors to computationally compensate for the relative motion, enabling fast processing without sacrificing measurement accuracy.
3Device complexity
If different sensor specimens are used without individual calibration, then device complexity is reduced, but measurement precision deteriorates due to systematic errors from geometric tolerances
Solution Approach 1:
The patent applies local quality by assigning individual velocity correction factors to each sensor specimen based on its specific geometric characteristics. Each sensor develops its own correction factor through calibration with a reference luminescent material, accounting for unique geometric tolerances in illumination and detection regions, ensuring accurate and comparable measurements across the sensor array.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The sensor accurately determines and corrects luminescence time constants at high transport velocities, ensuring consistent and comparable measurements across different sensor installations, thereby enhancing the authenticity verification of value documents.
Implementation Method 1
at least one photodetector for detecting the luminescence of the value document excited by the excitation light source
Implementation Method 2
at least one excitation light source for exciting a luminescence of the value document
Implementation Method 3
A value document to be verified may comprise one or a plurality of luminescent materials, in respect of which for example the decay time of the temporal intensity profile of the luminescence is/are verified
Data Source
AI summary
A sensor for verifying value documents and designed to determine the luminescence time constant of a value document that is moved past the sensor for verification purposes, and the provision of a velocity correction of the luminescence time constant of the value document in the sensor. The relative movement between the value document and the sensor causes movement effects, resulting in a distortion of the intensity curve from which the luminescence time constant is derived. The luminescence time constant is corrected using a sensor-specific corrective factor ascertained for the velocity of the movement of the value document during the verification process. For this purpose, different sensor-specific corrective factors are used for different examples of sensors that are nominally identical in design and are part of the same sensor production series.